The invention relates to a printed circuit board with at least one conductor path on a substrate with an electrically insulating surface serving as a carrier, wherein an electrically conducting and mechanically fast connection of the conductor path via contact pads is provided with a connection cable having at least two connecting wires mutually insulated from one another, as well as a process for producing a printed circuit board and for connecting the connecting wires, as well as a use of the printed circuit board.
A temperature sensor with a measuring resistor is known from DE 39 39 165, in which a small ceramic board serving as a carrier with a thin metal coating as a resistance layer is constructed, and contact surfaces are connected directly electrically conducting and mechanically fast with conductor paths electrically insulated from one another on a printed circuit board. A plastic foil, for example capton foil, is provided as a printed circuit board, wherein the conducting paths consist of copper or a copper-based alloy. The printed circuit board, which is located in a protective tube, is joined with an external connection cable via connecting pads, wherein the connecting cable is connected mechanically fast with the protective tube for the purpose of stress relief.
Furthermore, a fever thermometer is known from DE 31 27 727A1, in which a measuring resistance consisting of two component resistors is applied to a substrate board in thin layer technology, wherein the substrate is enclosed by a mass resistant to disinfectants, and external connection wires are connected with one end of the substrate board via solder points.
The known temperature sensors with printed circuit boards prove to be a problem in case a largely automated assembly is provided, since the alignment of the free ends of the connection cable with the provided solder contact surfaces requires an exact positioning. In practice, these assemblies require high standards with respect to the aptitude of the assembly personnel.
Furthermore, a temperature-measuring resistor consisting of a small ceramic board serving as a carrier with a thin metal coating as a resistance layer and contact surfaces, as well as an insulation layer protecting the resistance layer which is applied to a printed circuit board, is known from DE-GM 87 16 103. In order to provide a sure electrical and mechanical connection of the measuring resistor with a connection cable, the contact surfaces are connected directly electrically conducting and mechanically fast with the conductor paths of the printed circuit board. Even if a secure and largely automated application of the measuring resistor according to the description is to be expected, further-reaching measures for fastening and bonding a connection cable are not indicated.
Furthermore, a process for electrical bonding of printed circuit boards is known from DT 24 19 327 A1, in which electrically insulated wires in the form of conductor strips are inserted into borings of connector positions of the printed circuit board and joined by means of a solder pad. By connection of conductor strips with plugs and grip bands, a stress relief of the connector positions connected with the plug is accomplished. A possible stress relief of the connector positions on the printed circuit board is not provided.
An object of the invention is to create a largely automatable assembly of printed circuit boards, possibly in SMD technology. Moreover, a connection with stress relief between printed circuit board and at least one connecting wire should be achieved. Furthermore, a production process for printed circuit boards should be presented with which an economical manufacture is possible. In addition, a process for connecting connection wires and a use of the printed circuit boards should be indicated.
The object is accomplished in accordance with an arrangement of a printed circuit board having at least one conductor path with contact pads on an electrically insulting substrate surface being connectable by a melting process to lead wires stripped of their insulation from a jacketed connection cable, wherein an end of the cable is positioned in a mounting element fixedly arranged in relation to the conductor path at a distance from the contact pads.
The possibility of using standardized printed circuit board structures proves to be advantageous. In an advantageous configuration, mounting elements are provided with channel-shaped recesses for receiving jacketed cable ends, whose lead exit area is arranged adjacent to a respective contact surface. Here the possibility of automatable connection of connecting lands to contact pads of the conductor path proves to be beneficial. Further advantageous configurations of the arrangement are described and claimed hereinafter.
By connection of two or more contact pads with a conductor path, this can be favorably constructed as a resistance layer. It furthermore proves to be beneficial in connection with printed circuit boards that standard resistors adapted to the application in question can be used.
The object is further accomplished in accordance with the process for producing a printed circuit board, wherein the circuit board is manufactured as a monolithic preform by an injection molding process from plastic granulate, wherein a mounting element for receiving a jacketed connection cable end, projecting from a plane formed by the contact pads of the conductor path, is so constructed to include at least one channel-shaped recess with a cable-end exit area adjacent to at least one of the contact pads.
The sturdy connection technique of the conductor connections proves to be especially advantageous wherein the particular cable connection technique also makes possible manufacturing in the form of a panel with a field arrangement of measuring elements in a simple manner. A basic advantage of the process is to be seen in the possibility of automatic assembly of temperature sensors. In addition, quality control is essentially facilitated. Advantageous embodiments of the process are described and claim hereinafter.
The objective is moreover accomplished in accordance with the process for connecting cable ends to a printed circuit board, wherein the printed circuit board is inserted into a workpiece carrier and positioned above a solder jet with contact pads directed downwardly, wherein the cable is guided by a gripper along the printed circuit board longitudinal axis with its lead ends until it is arrested on a stop pin projecting upward between the lead ends, such that the cable ends with their jacket are inserted into recesses of the mounting, and the lead ends of the cable stripped of their insulation are situated below the contact pads and touch these, and that subsequently a solder flow or wave running out of the solder jet is conducted over the contact pads, which connects the lead wires stripped of their insulation to the contact pads in an electrically-conducting and mechanically-tight manner.
An advantageous configuration of the process is directed toward a joining of connecting cables with printed circuit boards which are, in addition, constructed as panels. The possibility of an economical manufacture owing to simultaneous processing of several printed circuit boards proves to be particularly favorable.
The object further is accomplished through use of the printed circuit boards of the invention for temperature sensors or heating elements. The object is also accomplished through use of the printed circuit boards as measurement electrodes.